If you haven't travelled Pratchett's Discworld yet, you're not alone. Mr. Twoflowers hasn't travelled it yet, and he lives there. Feel free to join him and his reluctant guide, Rincewind, as they sample Discworld's dives, tavern brawls, dragons, assassins, pirates, and a charming assortment of near-death experiences.
Twoflowers has the tourist's implacable confidence that every demonic temple, every hero with a magic sword, every brigand, and every catastrophe of nature was placed and scheduled for his amusement - and will hold still for a picture. He's also quite convinced that, as a tourist, he's immune to any possible harm.
That premise gives Pratchett's comic genius plenty to work with. Even Death - the Reaper himself - is just a straight man in this world. (There's also The Luggage, but I'll let you discover that for yourself.)
This is the first book in a long-lived series, and gets it off to a great start. I have to warn you, though, there's no such thing as one Pratchett book. Even one is enough to cause addiction.